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Old January 16, 2013, 01:20 PM   #1
44smith
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Sharp crack shooting 44 smith

I have 3 Smith 629's with 4" barrels. A 629-3 with 4" barrel that I've had for a long time. And two new 629-6's with 4" barrels
Using the same ammunition out of the same box: 240 grain hollow points.
The 629-3 and one of the new 629-6's have a loud, more dull sounding, boom when shot and kick straight up.
The other new 629-6 has a loud sharp crack when shot that affects the left side ear only and it kicks to the left a little.
Anyone know what would cause the sharp crack sound?
I can't figure out why the one is different than the other two on the same guns.
Thanks for the help.

Last edited by 44smith; January 17, 2013 at 11:44 PM.
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Old January 16, 2013, 03:25 PM   #2
Unclenick
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Welcome to the forum.

You may have the cart before the horse. It may kick left, and that's why the left ear hears it most. I would suspect a sharper crack if the barrel/cylinder gap were bigger. You might get out the automotive feeler gages to see. 0.004" to 0.006" seems to be pretty normal in these guns, though I did once have one with a 0.002" gap that would start to rub when it heated up.
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Old January 16, 2013, 06:04 PM   #3
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Unclenick, I measured the gap with the feeler guages and on the right side it is .0045, and on the left side it is .0075.
Shouldn't they be the same or close to the same on each side?
Thanks for the help.
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Old January 16, 2013, 06:19 PM   #4
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What conditions are you shooting under? Indoor or outdoor range? If outdoor, under some sort of roof? How high is it. What hearing protection do you wear-plugs and muffs, or just one or the other. Check your grip, and your grips-are they really comfortable for you?
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Old January 16, 2013, 06:27 PM   #5
44smith
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We shoot outdoor in the open, no roof, on our own property. Wear plugs, but have shot without some. One time with the one that cracks cause it hurt my left ear so much. Have shot the others without too and they don't have that really sharp crack. My grips are pretty comfortable.
Thanks
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Old January 16, 2013, 08:46 PM   #6
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I wonder if you're getting forcing cone strikes on the left. Any idea if it's spitting lead?
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Old January 16, 2013, 11:16 PM   #7
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It sounds like the forcing cone is cut unevenly. If the gun is new from the factory, I would call them and I think they will take it back and correct it. It is a simple job for a gunsmith with the right tools, but why pay to have a factory mistake corrected.

Jim
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Old January 16, 2013, 11:16 PM   #8
44smith
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Haven't noticed any lead spitting. Have only shot 12 shots through it. With the gap being larger on the left than right I've been wondering if that has something to do with it. Forcing cone stikes? Different pressure coming out of each side of the gap?
Haven't really shot pistol that much. In fact we've had the 629-3 for around 20 years and we are still on the second box of ammo. Mainly just packed it in the woods for protection. Check it once a year for accuracy and that's about it.
Thanks for the help.
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Old January 16, 2013, 11:24 PM   #9
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James K, I just got it back from S&W and they told me it was all within their spec. That anywhere from .004 to .010 is within specs. Even if the sides are uneven, each side is within specs. Don't sound right to me.
I'm trying to get other opinions on it from people with more knowledge than me. Then I will probably call them back again.
If I have a gunsmith do it I'm worried about loosing my warranty for further repair.
Thanks for the help.
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Old January 16, 2013, 11:31 PM   #10
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If you're worried about warrenty you could ask S&W to do it though you might have a wait.
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Old January 16, 2013, 11:34 PM   #11
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What do you think S&W would charge? Probably wouldn't do it for free beings it's within specs.
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Old January 17, 2013, 12:28 PM   #12
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A sharp crack can be a sonic boom. What ammo are you using?
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Old January 17, 2013, 01:38 PM   #13
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I'm using 240 gr. hollow point. It's the same box of ammunition that I've had for 15+ years and used in the 629-3 and the other 629-6 and they never made that loud crack. More of a loud dull boom. They are all 4" barrels. I'm not sure, but if it doesn't do it in one it shouldn't do it in the other unless there is something else making it do it, if my thinking is right.
I haven't shot revolver a lot so kind of short on knowledge on them.
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Old January 17, 2013, 04:44 PM   #14
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I think S&W is wrong this time but the uneven barrel has no effect on performance and safety. Still, IMHO, an uneven gap is not right even if both sides are within spec. Your choice as to whether to get a gunsmith to correct it. He will (should) use a facing cutter to even that barrel, which will leave both sides with the same .0075 gap.

Jim
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Old January 17, 2013, 05:16 PM   #15
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sonic boom

If I read right first dull boom shots were from a three inch barrel the sharper sound is from the 6 inch my thought is the six inch got enough velocity to hit sound barrier, went supersonic your hearing the sonic boom while the three inch barrel produced subsonic velocity. Hope your hearing it threw ear muffs or plugs
bb
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Old January 17, 2013, 05:35 PM   #16
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Jim, Do you think if I had the barrel evened up that .0075 gap would be fine? I know Smith said from .oo4 to .0010, but from what I read most like it around .004 or .005.
I don't know myself what pros or cons the bigger gap may cause, if any.
Thanks
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Old January 17, 2013, 05:38 PM   #17
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bb, All 3 629's are 4" barrel. I would think that if one would go supersonic they all should from the same length barrel, shouldn't they?
Thanks for the help.
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Old January 17, 2013, 06:51 PM   #18
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Is it possible the uneven gap is because the cylinder is not parallel to the barrel?
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Old January 17, 2013, 07:26 PM   #19
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musher, I was wondering that because if it was , the direction it's angled could cause the bullet to hit the left side of the forcing cone first, causing it to kick a little to the left before straightening out down the barrel. I mentioned that in the letter that I sent with the gun to S&W. But all they sent back for information is that everything meets S&W specs. Nothing about what they checked or anything. They called me and told me that the BC gap was within specs even though it was wider on one side than the other.
I'm not sure how to figure out if the cylinder is parallel to the barrel.
Thanks for the help.
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Old January 18, 2013, 09:56 AM   #20
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I'd focus more on how they shoot. What do they perform like, and is there any difference in accuracy? No? Then don't worry about it.
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Old January 18, 2013, 03:04 PM   #21
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Yeah, I was trying to imagine how to test that. Seems like you could at least measure whether the face of the forcing cone is square. It should protrude the same distance from the frame on each side if the inner face of the frame is flat.

If the forcing cone face is square to the barrel, wouldn't that imply the cylinder must be the part out of line?
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Old January 18, 2013, 04:22 PM   #22
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I'll have to try to check the cone for square to the barrel. If it is that would indicate the cylinder out of square.
I never thought of doing it that way.
Thanks
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Old January 19, 2013, 06:00 PM   #23
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Usually, with the feeler gauge you are trying to find one that slips all the way through from left to right between the back of the barre and the cylinder. If you have one that slips half way through from one side, but gets stuck on the way through and won't fit in at all from the other side, then, unless the frame is visibly bent or the cylinder visibly crooked in it looking down from above, I'd be suspicious that the back of the barrel isn't cut squarely. I don't know what kind of operation they use to cut that. I'd do it on a lathe, but they may saw it.

I would check the cylinder timing, too. Drag your thumb lightly against it while it turns to be sure the cylinder stop bolt clicks into the notch on the cylinder for every chamber. Put a white piece of paper between the frame and 12:00 chamber and look to see if the chambers are lining up with the bore. Look to see that the crack of light in the barrel/cylinder gap is even from top to bottom when looked at from the side.
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Old January 19, 2013, 08:59 PM   #24
44smith
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I can get .004 all the way thru from the right side and .007 about half way thru from the Left side. Looking down from the top the cylinder looks pretty square to the frame. But I don't know how easy it would be to see .003 out of square by looking. Might be easier to tell than I think.
I will try checking the timing too like you suggest. Do I need to have the revolver in lock down position while doing the timing (Pull hammer back, hold trigger down while lowering the hammer and then keep trigger held down while checking each chamber?
Thanks Unclenick
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Old January 19, 2013, 10:24 PM   #25
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Wow. Does sound like the back of the barrel is out of square. I think if you open the cylinder and lay a straight edge against the back end of the barrel and horizontal, you'll be able to see its edge not perfectly perpendicular to the barrel.

All you need to is cock the gun and let the hammer down. The bolt latch should stay in place until either it is cocked again or the trigger is pressed double-action style.

Looking down a gun barrel is not normally recommended, though I don't feel too badly about it if I open and check the cylinder and don't let the gun out of my hand until I'm done looking. If I do, I'll open and check the cylinder again. That said, the safest practice is to point it into a mirror and look at it that way. The mirror has the advantage that you can often bounce a flashlight off of it that illuminates the bore at the same time for a better view.
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